Mobile devices with a display, including cellular phones, smartphones, notebook personal computers, and tablet personal computers, have recently been widely used. A display is also used in in-vehicle equipment, such as car-mounted navigation systems.
A cover glass is often used for a display used in such a mobile device and in-vehicle equipment as described above. A flat glass plate is generally used as such a cover glass. However, from the operability, aesthetic, and other viewpoints, there are cases where a glass plate having a curved surface shape is desired as the cover glass.
Conventionally, as described in Patent Literature 1 and so on, a glass plate having a curved surface shape is manufactured by placing a flat glass plate on a forming die having a curved surface shape, heating the glass plate to a temperature of the softening point thereof or above to soften it, and deforming it along the shape of the forming die under its own weight.